Automatic transmission effective for changing speed by brake pressure

ABSTRACT

The automatic transmission system incorporates a hydraulic torque converter (which with its associated torque activated elements is hereinafter referred to as torcon). The aforesaid associated mechanisms or elements comprising a hydraulic torque converter pump, a hydraulic torque turbine, an associated multiple gear assembly, a friction engaging means for activating the appropriate elements of the speed change gearing of the multiple gear assembly and an oil pressure operation circuit, the same being effectuated by a signal generated by a brake pressure detector, the aforesaid mechanisms, assemblies and oil pressure operation circuit being activated electrically, or mechanically.

D United States Patent 1151 3,700,079

Shirai et a]. 1 Oct. 24, 1972 [$4] AUTOMATIC TRANSMISSION [56] References Cited E fi ggg g f gg SPEED UNITED STATES PATENTS [72] Inventors: Takeaki shin], Nagoya; shigem 3,001,415 9/1961 Smrrl 192/4 A X 2,872,000 2/1959 Herndon et al 192/4 A Samar" okada 2,931,251 4/1960 Wayman ..192/4 A x s i Nagoya; Mmharu 3,523,597 8/1970 bemieux ..192/4 A miyoshi, Toyota, all of Japan Primary Examiner-Benjamin W. Wyche [73] Assignees. Nippon Denso Kabushiki Kaisha,

Toyom Jidosha Kogyo Kabushnd AttorneyBlum, Moscovitz, Friedman & Kaplan [57] ABSTRACT {22] Filed: May 1970 The automatic transmission system incorporates a [21 Appl, No 37,150 hydraulic torque converter (which with its associated torque activated elements is hereinafter referred to as torcon). The aforesaid associated mechanisms or ele- [301 Foreign Application Priority Data ments comprising a hydraulic torque converter pump, a hydraulic torque turbine, an associated multiple gear y 24, 1969 Japan 44/40291 assembly, a friction engaging means for activating the appropriate elements of the speed change gearing of [52] U.S. Cl. ..192/4 A, 74/752 A the multiple gear assembly and an oil pressure opera- [51] 1111. C1. ..Fl6h 57/10, B601: 29/02 tion circuit, the same being effectuawd by a Signal [58] Field of Search ..192/4 A generated by a brake Pressure detecwrthe afmesaid mechanisms, assemblies and oil pressure operation circuit being activated electrically, or mechanically.

6 Claims, 29 Drawing Figures PHENTED B1 24 I973 SHEET DZUF 18 FIG 2,

PATENTEDUBT 24 I972 SHEET 03 [IF 18 FIG.3A.

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THE NUMBER OF REVOLUTIONS OF THE SHAFT OF HYDRAULIC TORQUE CONVERTER TURBINE N (RPM) COMPUTED IN CAR SPEED m m E E E955 Qtbq mmhmlzow whats 23 Q I b6 tqim m5 b6 mzota mm no mmmtbz m1 PATENTED 24 I97? 3. 7 00.0 7 9 saw us or 18 FIG.5A. FIG.5B.

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m J W TERMINAL VOLTAGE m2 (SOLENOID VOLTAGE) (J) TIME PKTENTEDncI 24 m2 SHEET [17 HF 18 FIG.14

INPUT VOLTAGE (SOLENOID vow/x65 DIFFERENTIATED VOLTAGE (e) RECTIFIED VOLTAGE W mm H OUTPUT VOLTAGE PA-IENTEnncI 24 m2 SHEET IBUF 18 com? gsmi QQ E PATENTEDUBI 24 I972 SHEET 17UF 18 PHE'N'TEBHBI 24 m2 SHEET lBDF 18 Bud;

SUMMARY OF THE INVENTION The present invention relates to an automatic transmission comprising a hydraulic torque converter to be used as the transmission for vehicles, the transmission elements associated with the hydraulic torque converter comprising multiple gear transmission mechanism, engaging means for selecting the appropriate speed change gearing of the multiple gear transmission mechanism, and an oil pressure operation circuit, wherein mechanism is provided for carrying out the engine brake operation (which is referred to as brake down" operation) in low gear state, upon efiectuation of speed change from high gear state into low gear state when the brake pressure attains a value beyond a predetermined value.

In the vehicles provided with conventional automatic transmission, the engine brake in most cases is not too efficient and although relatively high control can be obtained at a high cruising speed, nevertheless the efficiency of engine brake decreases as the vehicle speed is lowered.

Therefore, when engine brake is frequently employed, or when abrupt brake down is effectuated or in down slope cruising, in the conventional vehicle, the gearing of the gear transmission mechanism in most cases is manually lowered into one step lower gear state to attain the desired object.

Therefore, the aim of the present invention is to antomatize the above-mentioned brake down operation, and as an indispensable condition for automatizing the brake down operation, it is preferable to carry out the brake down operation when abrupt speed reduction is carried out by adding high pressure to the brake pedal although it may not be necessary to carry out brake down operation when only slow speed reduction is required, this latter being effectuated by applying low pushing pressure to the brake pedal.

On the other hand, for example, when down slope cruising is being maintained for a long time, it is preferable to carry out brake down operation when the vehicle is desired to be driven on at a predetermined speed without introducing speed acceleration.

Moreover, the brake down operation can be excellently effectuated when speed reduction is not required, as in the case in which a vehicle has completed its cruising on a curve, since the gear transmission mechanism at that stage is in low gear state, and line speed acceleration and excellent cruising efficiency can be obtained.

The main object of the present invention is to provide very convenient and effective automatic transmission having the efficiency for carrying out brake down operation automatically when brake pressure is large and without bringing about brake down operation when the engine brake pressure is small, in such a manner that an electric or oil pressure brake down signal is generated by means of utilization of brake pressure detector when brake pressure goes beyond the predetermined value, said signal being introduced into the automatic transmission which upon activation effectuates the speed change requisite to carry out brake down operation, such brake down operation being automatically effectuable without changing the main structure of said automatic transmission mechanism, by adding the brake pressure detector to the automatic transmission for carrying out normal cruising, the transmission being provided with hydraulic torque converter, friction engaging means, and oil pressure operation circuit as the major elements thereof.

The following is a detailed description of the structures and operations of the embodiments of the present invention:

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 is the cross sectional view of an embodiment of the transmission of the present invention;

FIG. 2 is a diagram showing the oil pressure operation circuit when an electric circuit is utilized for the control of the transmission as is shown in FIG. 1;

FIGS. 3A and 3B graphically illustrate speed change zones;

FIG. 4 is a block diagram showing the structure of the control assembly incorporating an electric circuitry system as an embodiment of the present invention;

FIG. 5A and 5B are the diagrams showing the structure of the rpm detecting circuit utilized in the control assembly as shown in FIG. 4;

FIG. 6 is a block diagram showing the structure of the rpm computation circuit in the aforesaid system;

FIG. 7 is a diagram showing the operation voltage wave of the rpm computation circuit;

FIG. 8 is a diagram showing the brake pressure detector;

FIG. 9 is a block diagram showing the structure of the rpm determining computation circuit;

FIG. 10 is a block diagram showing the structure of slip computation circuit;

FIG. 11 is a block diagram showing the structure of the bistable memorial circuit;

FIG. 12 is a diagram showing the operation voltage wave of the bistable memorial circuit, utilized in the aforesaid system;

FIG. 13 is a block diagram of the synchronous time retaining circuit;

FIG. 14 is a diagram showing the operation voltage wave of said synchronous time retaining circuit;

FIG. 15 is a block diagram showing the speed change position logical circuit;

FIG. 16 is a diagram of the time delay circuit;

FIG. 17 is a block diagram showing the state of the computation circuitry when a vehicle is cruising at a speed above km/h at highest gear position;

FIG. 18 is a block diagram showing the state of the computation circuitry when the brake down signal is generated as the brake pedal is pushed in when the vehicle is cruising under the above-mentioned condition shown in FIG. 17;

FIG. 19 is a block diagram showing the state of the computation circuitry when the synchronous time retaining signal is maintained after the brake down is brought into the second gear state from the top gear state by generation of the speed change signal;

FIG. 20 is a block diagram showing the state of computation circuitry when the synchronous time retaining signal is terminated after brake down into the second gear state from the top gear state;

FIG. 21 is a block diagram showing the state of the computation circuitry when the speed change signal is 

1. In an automatic vehicle transmission system for carrying out speed change by application of brake pressure, hydraulic torque converter means (10) including an input shaft (11), a pump (12) operatively connected to and driven by said input shaft (11), and a turbine (13) driven by said pump (12), a gear transmission means (50) operatively connected to said turbine (13) to be driven thereby and including speed change gearing (51, 52, 54, 55, 57), frictional engaging means (30) operatively connected with said speed change gearing of said gear transmission means (50) for actuating said speed change gearing, oil pressure operation circuit means (FIGS. 2 and 26) having a speed change region determining valve means (1260, 2260) and, communicating with the latter valve means, a distribution valve means (1270, 1290, 2270, 2290) for distributing operational oil to said friction engaging means (30) for controlling the latter, a brake pressure detector means (340, 2350) for generating a pressure signal when brake pressure attains a value beyond a predetermined value, memorial means (A1540, B1640, 2320) operatively connected with said distribution valve means (1270, 1290, 2270, 2290) and said brake pressure detector means (340,2350) for responding to a signal generated by the latter to operate said distribution valve means (1270, 1290, 2270, 2290) to control said friction engaging means (30) to act on said gear transmission means (50) for effecting a speed change from a higher gear state into a lower gear state, and a time delay circuit means (1930) operatively connected with said detector means (340) for transmitting a signal therefrom after brake pressure has been applied beyond a given time period.
 2. In an automatic vehicle transmission system for carrying out speed change by application of brake pressure, a hydraulic torque converter means (10) having an input shaft (11) and including a pump (12) connected to said input shaft (11) to be driven thereby, said converter means also including a turbine (13) driven by said pump (12), a gear transmission means (50) driven by said turbine (13) and including speed change gearing (51, 52, 54, 55, 57) and an output shaft (56), friction engaging means (30) operatively connected to said transmission means (50) for actuating thE speed change gearing thereof, an oil pressure operating circuit means (FIG. 2) having a speed change region determining valve means (1260) and, communicating therewith, a distribution valve means (1270, 1290), said latter valve means communicating with said friction engaging means (30) for distributing operation oil thereto to control actuation of the latter, plurality of computation circuit means (1310, 1410, 1420, 1430, 1440, 1450, 1460, 1320,1330, 1340, 1350,1360, 1370) operatively connected with said converter means (10) and said transmission means (50) for generating a plurality speed change signals for effecting speed change from a higher into a lower gear state and for generating a plurality of speed change signals for effecting speed change into a higher gear state when the slip ratio of the number of revolutions of said pump shaft (11) with respect to the number of revolutions of said turbine (13) is at a predetermined value and when the number of revolutions of said turbine (13) and the number of revolutions of said output shaft (56) of said transmission means (50) are at predetermined values, a first AND-circuit means (A1510, C1610) connected electrically to some of said computation circuit means for generating an output signal when a plural number of speed change signals for converting said gear transmission means (50) into a higher gear state are generated, OR-circuit means (A1530, B1630) electrically connected with others of said plurality of computation circuit means for generating an output signal when any one of a plural number of speed change signals for changing said gear transmission mechanism into a lower gear state are generated, second AND-circuit means (B1520, D1620) electrically connected with said OR-circuit means (A1530, B1630) for receiving signals therefrom, bistable memorial circuit means (A1540, B1640) connected electrically with said first AND-circuit means (A1510, C1610) and with said second AND-circuit means (B1520, D1620) for continuously eliminating output signals as said bistable memorial circuit means is activated into counter stable state by a signal introduced from said OR-circuit means through said second AND-circuit means and for maintaining output signals in the normal stable state by signals received from said first AND-circuit means, synchronous time retaining circuit means (1710) operatively connected with said memorial circuit means (A1540, B1640) for generating a synchronous time retaining signal for predetermined time from the time when the output signal is generated and extinguished by said memorial circuit means, said synchronous time retaining circuit means being electrically connected with said first and second AND-circuit means, a NOT-circuit means (1720) electrically connected to said synchronous time retaining circuit means (1710) for extinguishing output signals during the time when the synchronous time retaining signal from said time retaining circuit means is developed in the circuit from said synchronous time retaining means to said first and second AND-circuit means, gear position logic circuit means (1810) electrically connected with said memorial circuit means (A1540, B1640) and with said synchronous time retaining circuit means (1710) as well as with said first and second AND-circuit means for adding a lower gear position signal to said first AND-circuit means by generating a lower gear position signal when a signal is not introduced from said memorial circuit means and for generating a higher gear position when a signal is introduced from said memorial circuit means and for adding said higher gear position signal to second AND-circuit means when said higher gear position signal is introduced from said memorial circuit means, electrical actuator means (1280, 1300) operatively connected to said distribution valve means (1270, 1290) for operating the latter when the output signal from said memorial circuit means is added, and brake-pressure detector means (340) fOr generating a signal when brake pressure attains a valve beyond a predetermined pressure, said detector means (340) being electrically connected with said OR-circuit means so that when a signal is generated by said detector means said distribution valve means (1270, 1290) is operated to carry out a speed change from a higher gear state into a lower gear state.
 3. The combination of claim 2 and wherein a third AND-circuit means (E1910, F1920) is electrically connected with said OR-circuit means as well as with some of said computation circuit means and said detector means (340) for bringing about speed change from a higher gear state into a lower gear state by operation of said distribution valve means (1270, 1290) when the number of revolutions of said output shaft (56) is below a predetermined number of revolutions and is introduced to said third AND-circuit means (E1910, F1920) when the latter signal and a signal from said detector means are both added to said third AND-circuit means (E1910, F1920).
 4. The combination of claim 2 and wherein a time delay circuit means (1930) is electrically connected with said detector means (340) for bringing about operation of said distribution valve means (1270, 1290) to provide a speed change from a higher gear state into a lower gear state only when a signal is generated from said detector means (340) for more than a predetermined time.
 5. In an automatic vehicle transmission system for carrying out speed change by application of brake pressure, hydraulic torque converter means (10) including an input shaft (11), a pump (12) operatively connected to and driven by said input shaft (11), and a turbine (13) driven by said pump (12), a gear transmission means (50) operatively connected to said turbine (13) to be driven thereby and including speed change gearing (51, 52, 54, 55, 57), frictional engaging means (30) operatively connected with said speed change gearing of said gear transmission means (50) for actuating said speed change gearing, oil pressure operation circuit means (FIGS. 2 and 26) having a speed change region determining valve means (1260, 2260) and, communicating with the latter valve means, a distribution valve means (1270, 1290, 2270, 2290) for distributing operational oil to said friction engaging means (30) for controlling the latter, a brake pressure detector means (340,2350) for generating a pressure signal when brake pressure attains a value beyond a predetermined value, hydraulic memorial means (2320) operatively connected with said distribution valve means (1270, 1290, 2270, 2290) and said brake pressure detector means (340, 2350) for responding to a signal generated by the latter to operate said distribution valve means (1270, 1290, 2270, 2290) to control said friction engaging means (30) to act on said gear transmission means (50) for effecting a speed change from a higher gear state into a lower gear state.
 6. In an automatic vehicle transmission system for carrying out speed change by application of brake pressure, hydraulic torque converter means (10) including an input shaft (11), a pump (12) operatively connected to and driven by said input shaft (11), and a turbine (13) driven by said pump (12), a gear transmission means (50) operatively connected to said turbine (13) to be driven thereby and including speed change gearing (51, 52, 54, 55, 57), frictional engaging means (30) operatively connected with said speed change gearing of said gear transmission means (50) for actuating said speed change gearing, oil pressure operation circuit means (FIGS. 2 and 26) having a speed change region determining valve means (1260, 2260) and, communicating with the latter valve means, a distribution valve means (1270, 1290, 2270, 2290) for distributing operational oil to said friction engaging means (30) for controlling the latter, a brake pressure detector means (340, 2350) for generating a pressure signal when brake pressure attains a value beyond a predetermined value, and electrical memoriAl means (A1540, B1640) operatively connected with said distribution valve means (1270, 1290, 2270, 2290) and said brake pressure detector means (340, 2350) for responding to a signal generated by the latter to operate said distribution valve means (1270, 1290, 2270, 2290) to control said friction engaging means (30) to act on said gear transmission means (50) for effecting a speed change from a higher gear state into a lower gear state. 